/*
** $Id: ldo.c,v 2.108 2012/10/01 14:05:04 roberto Exp $
** Stack and Call structure of Lua
** See Copyright Notice in lua.h
*/


#include <setjmp.h>
#include <stdlib.h>
#include <string.h>

#define ldo_c
#define LUA_CORE

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lopcodes.h"
#include "lparser.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"
#include "lzio.h"




/*
** {======================================================
** Error-recovery functions
** =======================================================
*/

/*
** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
** default, Lua handles errors with exceptions when compiling as
** C++ code, with _longjmp/_setjmp when asked to use them, and with
** longjmp/setjmp otherwise.
*/
#if !defined(LUAI_THROW)

#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
/* C++ exceptions */
#define LUAI_THROW(L,c)		throw(c)
#define LUAI_TRY(L,c,a) \
	try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
#define luai_jmpbuf		int  /* dummy variable */

#elif defined(LUA_USE_ULONGJMP)
/* in Unix, try _longjmp/_setjmp (more efficient) */
#define LUAI_THROW(L,c)		_longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a)		if (_setjmp((c)->b) == 0) { a }
#define luai_jmpbuf		jmp_buf

#else
/* default handling with long jumps */
#define LUAI_THROW(L,c)		longjmp((c)->b, 1)
#define LUAI_TRY(L,c,a)		if (setjmp((c)->b) == 0) { a }
#define luai_jmpbuf		jmp_buf

#endif

#endif



/* chain list of long jump buffers */
struct lua_longjmp {
	struct lua_longjmp *previous;
	luai_jmpbuf b;
	volatile int status;  /* error code */
};


static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
	switch (errcode) {
	case LUA_ERRMEM: {  /* memory error? */
		setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
		break;
					 }
	case LUA_ERRERR: {
		setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
		break;
					 }
	default: {
		setobjs2s(L, oldtop, L->top - 1);  /* error message on current top */
		break;
			 }
	}
	L->top = oldtop + 1;
}


l_noret luaD_throw (lua_State *L, int errcode) {
	if (L->errorJmp) {  /* thread has an error handler? */
		L->errorJmp->status = errcode;  /* set status */
		LUAI_THROW(L, L->errorJmp);  /* jump to it */
	}
	else {  /* thread has no error handler */
		L->status = cast_byte(errcode);  /* mark it as dead */
		if (G(L)->mainthread->errorJmp) {  /* main thread has a handler? */
			setobjs2s(L, G(L)->mainthread->top++, L->top - 1);  /* copy error obj. */
			luaD_throw(G(L)->mainthread, errcode);  /* re-throw in main thread */
		}
		else {  /* no handler at all; abort */
			if (G(L)->panic) {  /* panic function? */
				lua_unlock(L);
				G(L)->panic(L);  /* call it (last chance to jump out) */
			}
			abort();
		}
	}
}


int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
	unsigned short oldnCcalls = L->nCcalls;
	struct lua_longjmp lj;
	lj.status = LUA_OK;
	lj.previous = L->errorJmp;  /* chain new error handler */
	L->errorJmp = &lj;
	LUAI_TRY(L, &lj,
		(*f)(L, ud);
	);
	L->errorJmp = lj.previous;  /* restore old error handler */
	L->nCcalls = oldnCcalls;
	return lj.status;
}

/* }====================================================== */


static void correctstack (lua_State *L, TValue *oldstack) {
	CallInfo *ci;
	GCObject *up;
	L->top = (L->top - oldstack) + L->stack;
	for (up = L->openupval; up != NULL; up = up->gch.next)
		gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
	for (ci = L->ci; ci != NULL; ci = ci->previous) {
		ci->top = (ci->top - oldstack) + L->stack;
		ci->func = (ci->func - oldstack) + L->stack;
		if (isLua(ci))
			ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
	}
}


/* some space for error handling */
#define ERRORSTACKSIZE	(LUAI_MAXSTACK + 200)


void luaD_reallocstack (lua_State *L, int newsize) {
	TValue *oldstack = L->stack;
	int lim = L->stacksize;
	lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
	lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
	luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
	for (; lim < newsize; lim++)
		setnilvalue(L->stack + lim); /* erase new segment */
	L->stacksize = newsize;
	L->stack_last = L->stack + newsize - EXTRA_STACK;
	correctstack(L, oldstack);
}


void luaD_growstack (lua_State *L, int n) {
	int size = L->stacksize;
	if (size > LUAI_MAXSTACK)  /* error after extra size? */
		luaD_throw(L, LUA_ERRERR);
	else {
		int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
		int newsize = 2 * size;
		if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
		if (newsize < needed) newsize = needed;
		if (newsize > LUAI_MAXSTACK) {  /* stack overflow? */
			luaD_reallocstack(L, ERRORSTACKSIZE);
			luaG_runerror(L, "stack overflow");
		}
		else
			luaD_reallocstack(L, newsize);
	}
}


static int stackinuse (lua_State *L) {
	CallInfo *ci;
	StkId lim = L->top;
	for (ci = L->ci; ci != NULL; ci = ci->previous) {
		lua_assert(ci->top <= L->stack_last);
		if (lim < ci->top) lim = ci->top;
	}
	return cast_int(lim - L->stack) + 1;  /* part of stack in use */
}


void luaD_shrinkstack (lua_State *L) {
	int inuse = stackinuse(L);
	int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
	if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
	if (inuse > LUAI_MAXSTACK ||  /* handling stack overflow? */
		goodsize >= L->stacksize)  /* would grow instead of shrink? */
		condmovestack(L);  /* don't change stack (change only for debugging) */
	else
		luaD_reallocstack(L, goodsize);  /* shrink it */
}


void luaD_hook (lua_State *L, int event, int line) {
	lua_Hook hook = L->hook;
	if (hook && L->allowhook) {
		CallInfo *ci = L->ci;
		ptrdiff_t top = savestack(L, L->top);
		ptrdiff_t ci_top = savestack(L, ci->top);
		lua_Debug ar;
		ar.event = event;
		ar.currentline = line;
		ar.i_ci = ci;
		luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
		ci->top = L->top + LUA_MINSTACK;
		lua_assert(ci->top <= L->stack_last);
		L->allowhook = 0;  /* cannot call hooks inside a hook */
		ci->callstatus |= CIST_HOOKED;
		lua_unlock(L);
		(*hook)(L, &ar);
		lua_lock(L);
		lua_assert(!L->allowhook);
		L->allowhook = 1;
		ci->top = restorestack(L, ci_top);
		L->top = restorestack(L, top);
		ci->callstatus &= ~CIST_HOOKED;
	}
}


static void callhook (lua_State *L, CallInfo *ci) {
	int hook = LUA_HOOKCALL;
	ci->u.l.savedpc++;  /* hooks assume 'pc' is already incremented */
	if (isLua(ci->previous) &&
		GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
			ci->callstatus |= CIST_TAIL;
			hook = LUA_HOOKTAILCALL;
	}
	luaD_hook(L, hook, -1);
	ci->u.l.savedpc--;  /* correct 'pc' */
}


static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
	int i;
	int nfixargs = p->numparams;
	StkId base, fixed;
	lua_assert(actual >= nfixargs);
	/* move fixed parameters to final position */
	fixed = L->top - actual;  /* first fixed argument */
	base = L->top;  /* final position of first argument */
	for (i=0; i<nfixargs; i++) {
		setobjs2s(L, L->top++, fixed + i);
		setnilvalue(fixed + i);
	}
	return base;
}


static StkId tryfuncTM (lua_State *L, StkId func) {
	const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
	StkId p;
	ptrdiff_t funcr = savestack(L, func);
	if (!ttisfunction(tm))
		luaG_typeerror(L, func, "call");
	/* Open a hole inside the stack at `func' */
	for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
	incr_top(L);
	func = restorestack(L, funcr);  /* previous call may change stack */
	setobj2s(L, func, tm);  /* tag method is the new function to be called */
	return func;
}



#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))


/*
** returns true if function has been executed (C function)
*/
int luaD_precall (lua_State *L, StkId func, int nresults) {
	lua_CFunction f;
	CallInfo *ci;
	int n;  /* number of arguments (Lua) or returns (C) */
	ptrdiff_t funcr = savestack(L, func);
	switch (ttype(func)) {
	case LUA_TLCF:  /* light C function */
		f = fvalue(func);
		goto Cfunc;
	case LUA_TCCL: {  /* C closure */
		f = clCvalue(func)->f;
Cfunc:
		luaD_checkstack(L, LUA_MINSTACK);  /* ensure minimum stack size */
		ci = next_ci(L);  /* now 'enter' new function */
		ci->nresults = nresults;
		ci->func = restorestack(L, funcr);
		ci->top = L->top + LUA_MINSTACK;
		lua_assert(ci->top <= L->stack_last);
		ci->callstatus = 0;
		luaC_checkGC(L);  /* stack grow uses memory */
		if (L->hookmask & LUA_MASKCALL)
			luaD_hook(L, LUA_HOOKCALL, -1);
		lua_unlock(L);
		n = (*f)(L);  /* do the actual call */
		lua_lock(L);
		api_checknelems(L, n);
		luaD_poscall(L, L->top - n);
		return 1;
				   }
	case LUA_TLCL: {  /* Lua function: prepare its call */
		StkId base;
		Proto *p = clLvalue(func)->p;
		luaD_checkstack(L, p->maxstacksize);
		func = restorestack(L, funcr);
		n = cast_int(L->top - func) - 1;  /* number of real arguments */
		for (; n < p->numparams; n++)
			setnilvalue(L->top++);  /* complete missing arguments */
		base = (!p->is_vararg) ? func + 1 : adjust_varargs(L, p, n);
		ci = next_ci(L);  /* now 'enter' new function */
		ci->nresults = nresults;
		ci->func = func;
		ci->u.l.base = base;
		ci->top = base + p->maxstacksize;
		lua_assert(ci->top <= L->stack_last);
		ci->u.l.savedpc = p->code;  /* starting point */
		ci->callstatus = CIST_LUA;
		L->top = ci->top;
		luaC_checkGC(L);  /* stack grow uses memory */
		if (L->hookmask & LUA_MASKCALL)
			callhook(L, ci);
		return 0;
				   }
	default: {  /* not a function */
		func = tryfuncTM(L, func);  /* retry with 'function' tag method */
		return luaD_precall(L, func, nresults);  /* now it must be a function */
			 }
	}
}


int luaD_poscall (lua_State *L, StkId firstResult) {
	StkId res;
	int wanted, i;
	CallInfo *ci = L->ci;
	if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
		if (L->hookmask & LUA_MASKRET) {
			ptrdiff_t fr = savestack(L, firstResult);  /* hook may change stack */
			luaD_hook(L, LUA_HOOKRET, -1);
			firstResult = restorestack(L, fr);
		}
		L->oldpc = ci->previous->u.l.savedpc;  /* 'oldpc' for caller function */
	}
	res = ci->func;  /* res == final position of 1st result */
	wanted = ci->nresults;
	L->ci = ci = ci->previous;  /* back to caller */
	/* move results to correct place */
	for (i = wanted; i != 0 && firstResult < L->top; i--)
		setobjs2s(L, res++, firstResult++);
	while (i-- > 0)
		setnilvalue(res++);
	L->top = res;
	return (wanted - LUA_MULTRET);  /* 0 iff wanted == LUA_MULTRET */
}


/*
** Call a function (C or Lua). The function to be called is at *func.
** The arguments are on the stack, right after the function.
** When returns, all the results are on the stack, starting at the original
** function position.
*/
void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
	if (++L->nCcalls >= LUAI_MAXCCALLS) {
		if (L->nCcalls == LUAI_MAXCCALLS)
			luaG_runerror(L, "C stack overflow");
		else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
			luaD_throw(L, LUA_ERRERR);  /* error while handing stack error */
	}
	if (!allowyield) L->nny++;
	if (!luaD_precall(L, func, nResults))  /* is a Lua function? */
		luaV_execute(L);  /* call it */
	if (!allowyield) L->nny--;
	L->nCcalls--;
}


static void finishCcall (lua_State *L) {
	CallInfo *ci = L->ci;
	int n;
	lua_assert(ci->u.c.k != NULL);  /* must have a continuation */
	lua_assert(L->nny == 0);
	if (ci->callstatus & CIST_YPCALL) {  /* was inside a pcall? */
		ci->callstatus &= ~CIST_YPCALL;  /* finish 'lua_pcall' */
		L->errfunc = ci->u.c.old_errfunc;
	}
	/* finish 'lua_callk'/'lua_pcall' */
	adjustresults(L, ci->nresults);
	/* call continuation function */
	if (!(ci->callstatus & CIST_STAT))  /* no call status? */
		ci->u.c.status = LUA_YIELD;  /* 'default' status */
	lua_assert(ci->u.c.status != LUA_OK);
	ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
	lua_unlock(L);
	n = (*ci->u.c.k)(L);
	lua_lock(L);
	api_checknelems(L, n);
	/* finish 'luaD_precall' */
	luaD_poscall(L, L->top - n);
}


static void unroll (lua_State *L, void *ud) {
	UNUSED(ud);
	for (;;) {
		if (L->ci == &L->base_ci)  /* stack is empty? */
			return;  /* coroutine finished normally */
		if (!isLua(L->ci))  /* C function? */
			finishCcall(L);
		else {  /* Lua function */
			luaV_finishOp(L);  /* finish interrupted instruction */
			luaV_execute(L);  /* execute down to higher C 'boundary' */
		}
	}
}


/*
** check whether thread has a suspended protected call
*/
static CallInfo *findpcall (lua_State *L) {
	CallInfo *ci;
	for (ci = L->ci; ci != NULL; ci = ci->previous) {  /* search for a pcall */
		if (ci->callstatus & CIST_YPCALL)
			return ci;
	}
	return NULL;  /* no pending pcall */
}


static int recover (lua_State *L, int status) {
	StkId oldtop;
	CallInfo *ci = findpcall(L);
	if (ci == NULL) return 0;  /* no recovery point */
	/* "finish" luaD_pcall */
	oldtop = restorestack(L, ci->extra);
	luaF_close(L, oldtop);
	seterrorobj(L, status, oldtop);
	L->ci = ci;
	L->allowhook = ci->u.c.old_allowhook;
	L->nny = 0;  /* should be zero to be yieldable */
	luaD_shrinkstack(L);
	L->errfunc = ci->u.c.old_errfunc;
	ci->callstatus |= CIST_STAT;  /* call has error status */
	ci->u.c.status = status;  /* (here it is) */
	return 1;  /* continue running the coroutine */
}


/*
** signal an error in the call to 'resume', not in the execution of the
** coroutine itself. (Such errors should not be handled by any coroutine
** error handler and should not kill the coroutine.)
*/
static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
	L->top = firstArg;  /* remove args from the stack */
	setsvalue2s(L, L->top, luaS_new(L, msg));  /* push error message */
	api_incr_top(L);
	luaD_throw(L, -1);  /* jump back to 'lua_resume' */
}


/*
** do the work for 'lua_resume' in protected mode
*/
static void resume (lua_State *L, void *ud) {
	int nCcalls = L->nCcalls;
	StkId firstArg = cast(StkId, ud);
	CallInfo *ci = L->ci;
	if (nCcalls >= LUAI_MAXCCALLS)
		resume_error(L, "C stack overflow", firstArg);
	if (L->status == LUA_OK) {  /* may be starting a coroutine */
		if (ci != &L->base_ci)  /* not in base level? */
			resume_error(L, "cannot resume non-suspended coroutine", firstArg);
		/* coroutine is in base level; start running it */
		if (!luaD_precall(L, firstArg - 1, LUA_MULTRET))  /* Lua function? */
			luaV_execute(L);  /* call it */
	}
	else if (L->status != LUA_YIELD)
		resume_error(L, "cannot resume dead coroutine", firstArg);
	else {  /* resuming from previous yield */
		L->status = LUA_OK;
		ci->func = restorestack(L, ci->extra);
		if (isLua(ci))  /* yielded inside a hook? */
			luaV_execute(L);  /* just continue running Lua code */
		else {  /* 'common' yield */
			if (ci->u.c.k != NULL) {  /* does it have a continuation? */
				int n;
				ci->u.c.status = LUA_YIELD;  /* 'default' status */
				ci->callstatus |= CIST_YIELDED;
				lua_unlock(L);
				n = (*ci->u.c.k)(L);  /* call continuation */
				lua_lock(L);
				api_checknelems(L, n);
				firstArg = L->top - n;  /* yield results come from continuation */
			}
			luaD_poscall(L, firstArg);  /* finish 'luaD_precall' */
		}
		unroll(L, NULL);
	}
	lua_assert(nCcalls == L->nCcalls);
}


LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
	int status;
	lua_lock(L);
	luai_userstateresume(L, nargs);
	L->nCcalls = (from) ? from->nCcalls + 1 : 1;
	L->nny = 0;  /* allow yields */
	api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
	status = luaD_rawrunprotected(L, resume, L->top - nargs);
	if (status == -1)  /* error calling 'lua_resume'? */
		status = LUA_ERRRUN;
	else {  /* yield or regular error */
		while (status != LUA_OK && status != LUA_YIELD) {  /* error? */
			if (recover(L, status))  /* recover point? */
				status = luaD_rawrunprotected(L, unroll, NULL);  /* run continuation */
			else {  /* unrecoverable error */
				L->status = cast_byte(status);  /* mark thread as `dead' */
				seterrorobj(L, status, L->top);
				L->ci->top = L->top;
				break;
			}
		}
		lua_assert(status == L->status);
	}
	L->nny = 1;  /* do not allow yields */
	L->nCcalls--;
	lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
	lua_unlock(L);
	return status;
}


LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
	CallInfo *ci = L->ci;
	luai_userstateyield(L, nresults);
	lua_lock(L);
	api_checknelems(L, nresults);
	if (L->nny > 0) {
		if (L != G(L)->mainthread)
			luaG_runerror(L, "attempt to yield across a C-call boundary");
		else
			luaG_runerror(L, "attempt to yield from outside a coroutine");
	}
	L->status = LUA_YIELD;
	ci->extra = savestack(L, ci->func);  /* save current 'func' */
	if (isLua(ci)) {  /* inside a hook? */
		api_check(L, k == NULL, "hooks cannot continue after yielding");
	}
	else {
		if ((ci->u.c.k = k) != NULL)  /* is there a continuation? */
			ci->u.c.ctx = ctx;  /* save context */
		ci->func = L->top - nresults - 1;  /* protect stack below results */
		luaD_throw(L, LUA_YIELD);
	}
	lua_assert(ci->callstatus & CIST_HOOKED);  /* must be inside a hook */
	lua_unlock(L);
	return 0;  /* return to 'luaD_hook' */
}


int luaD_pcall (lua_State *L, Pfunc func, void *u,
				ptrdiff_t old_top, ptrdiff_t ef) {
					int status;
					CallInfo *old_ci = L->ci;
					lu_byte old_allowhooks = L->allowhook;
					unsigned short old_nny = L->nny;
					ptrdiff_t old_errfunc = L->errfunc;
					L->errfunc = ef;
					status = luaD_rawrunprotected(L, func, u);
					if (status != LUA_OK) {  /* an error occurred? */
						StkId oldtop = restorestack(L, old_top);
						luaF_close(L, oldtop);  /* close possible pending closures */
						seterrorobj(L, status, oldtop);
						L->ci = old_ci;
						L->allowhook = old_allowhooks;
						L->nny = old_nny;
						luaD_shrinkstack(L);
					}
					L->errfunc = old_errfunc;
					return status;
}



/*
** Execute a protected parser.
*/
struct SParser {  /* data to `f_parser' */
	ZIO *z;
	Mbuffer buff;  /* dynamic structure used by the scanner */
	Dyndata dyd;  /* dynamic structures used by the parser */
	const char *mode;
	const char *name;
};


static void checkmode (lua_State *L, const char *mode, const char *x) {
	if (mode && strchr(mode, x[0]) == NULL) {
		luaO_pushfstring(L,
			"attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
		luaD_throw(L, LUA_ERRSYNTAX);
	}
}


static void f_parser (lua_State *L, void *ud) {
	int i;
	Closure *cl;
	struct SParser *p = cast(struct SParser *, ud);
	int c = zgetc(p->z);  /* read first character */
	if (c == LUA_SIGNATURE[0]) {
		checkmode(L, p->mode, "binary");
		cl = luaU_undump(L, p->z, &p->buff, p->name);
	}
	else {
		checkmode(L, p->mode, "text");
		cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
	}
	lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
	for (i = 0; i < cl->l.nupvalues; i++) {  /* initialize upvalues */
		UpVal *up = luaF_newupval(L);
		cl->l.upvals[i] = up;
		luaC_objbarrier(L, cl, up);
	}
}


int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
						  const char *mode) {
							  struct SParser p;
							  int status;
							  L->nny++;  /* cannot yield during parsing */
							  p.z = z; p.name = name; p.mode = mode;
							  p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
							  p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
							  p.dyd.label.arr = NULL; p.dyd.label.size = 0;
							  luaZ_initbuffer(L, &p.buff);
							  status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
							  luaZ_freebuffer(L, &p.buff);
							  luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
							  luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
							  luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);
							  L->nny--;
							  return status;
}


